The party was founded in 1944 by the illegal Communist Party of Switzerland. On May 21 the constituent conference of the Basel Federation of the party was held. On October 14–15 the same year the first Party Congress of the party was held in Zürich. Léon Nicole was elected President and Karl Hofmaier General Secretary.

On October 6–7, 1945 the Second Congress was held in Geneva. By this time the party has 20 000 members. On November 30-December 1 the 3rd Congress in Zürich.

On July 27 a Swiss Party Conference was held in Bern. Karl Hofmaier was removed from his position due to a financial scandal.

Holding two seats in the Swiss National Council (the lower or first chamber of the Swiss parliament) going into the 2007 elections, the party stood candidates in the cantons of Zürich, Vaud, Geneva and the Ticino on their own; in Neuchâtel the candidate appeared on a joint list with Solidarity. While the share of the vote in 2007 was similar to the party's 2003 results (0.7%), the party lost the seat held by Josef Zisyadis, while retaining the seat held by Marianne Huguenin.[5] However, on 1 November 2007 Marianne Huguenin announced her resignation from the National Council to focus on her position as mayor of Renens, Vaud, leaving Zisyadis to take the Party's seat in the National Council representing Vaud.[6]